The present invention relates to safety mechanisms. More particularly, the invention relates to a safety mechanism for a plumbing fixture.
It is common practice to provide a common duct or pipe for hot and cold running water. This arrangement is convenient because it permits the user to choose temperatures for the water which are intermediate between those of the hot and cold water. The arrangement has an inherent disadvantage, however: it is not uncommon for a person using the fixture to be scalded or at least uncomfortably burned. The problem is that the last person using the hot water often fails to flush the common line with cold water before leaving it for the next person to use. The next person, assuming that turning on the cold-water faucet will result in cold running water leaving the common pipe, turns on the cold-water tap, places his or her hands under the common pipe, and receives a discharge of very hot water before the cold water has displaced the residual hot water left from previous use.
The prior art is replete with mechanisms for blending hot and cold water prior to discharge, and with safety devices for interrupting the flow of water above a given temperature. See, for example, U.S. Pat. Nos. 3,648,724, 3,696,996, 3,938,741, and 4,563,780. This art, however, precludes uninterrupted separate discharges of very hot and of cold water through a common spout, on demand, in a failsafe manner; and this represents a very serious disadvantage.